1.3 - The convenience update

Adds regex search-replace ! Press Ctrl+R, choose your input file, your output file, a regular expression and a string to replace it with and the program will handle everything else !
Adds change history ! You can now undo your mistakes with Ctrl+Z and redo things with either Ctrl+Shift+Z or Ctrl+Y. (some operations like search-replace will need several undo to cancel completely)
Adds copy and pasting for entire cells. Select a cell and use Ctrl+C to copy its content, select one or more cell and use Ctrl+V to paste your clipboard's content into the selected cells.
Now automatically switches to edit mode as soon as you start typing in an editable cell.
You can now delete the content of a cell by using the del key.